

const pi = Math.PI;
//函数
module.exports = (radius) => {
 
  return{
    area(){
      return pi * radius * radius;
    },
    diameter(){
      return 2*radius;
    },
    circumference(){
      return pi * radius *radius;
    }
  };

};
    


console.log(module);

console.log('hello','world');
